Process for desalting petroleum



`asn. 20, 1942.

S. E. CAMPBELL PROCESS FOR DESALVTING PETROLEUM ma/er/ 29 Filed Jan. 26. 1939 Patented Jan. 2C, lg42 QFFEC 7 Claims.

This invention relates to improvements in reducing the salt content of petroleum and has principal reference to the removal of solid salts from crude petroleum.

An object of the invention is to so treat petroleum containing salt particles that such particlesare dissolved and then removed from the petroleum.

Another object is to so treat petroleum containing salt particles and saline water that the petroleum is desalted and dehydrated.

A further object is to so treat an emulsied petroleum containing salt particles that the salt and Water are removed from the petroleum as a saline solution.

It is known that much crude petroleum is produc'ed which contains saline water composed of solutions of various salts, such as the chlorides of sodium, magnesium, calcium, and the like, and very often such saline water forms a tenacious emulsion dicult to break.

In addition to such saline water, the petroleum often contains particles of solid salt which are diflcultly removable from the oil during the ordinarytreatments for dehydration inasmuch as they are enveloped by a tough lm of wax or other constituent which-prevents access of water to the solid-salt and in consequence they pass ,through dehydration apparatus with the oil and "on subsequent distillation, treatment, or use, cause immense damage toY apparatus in which the petroleum is treated or used.

An object of the invention is to provide a process and apparatus for continuously desalting and dehydrating petroleum in a novel, simple, and highly emcacious manner,

Referring to the drawing, in which- Fig. 1 shows a diagram, partly in section, showing apparatus suitable for the process;

Fig. 2 showsa modication of Fig. 1, and by reference to Fig. l it is explained that crude petroleum containing solid salt particles and saline water is brought through pipe I to a pump II which forces the oil through pipe I2, heat exchanger I3, and pipe Itl to a heater I5, in which its temperature is raised to a necessary degree to aid in the operation such being of the order of from 190 to 210 F., but the invention is not limited to such range of temperatures as the process is quite effective with certain oils at much lower temperatures.

The heated oil ows from heater I5 through pipe I6 to the bottom of any suitable mixing device Il in which it is violently agitated and thence through pipe I8 to a distributor I@ in the bottom of a contact tower 20. Tower 20 may be about four to ve times as tall as its diameter and contains a perforated support 2l on which is placed suitable graded contact material a, b, and c, such as quartz. For eiiicient operation, it is found that the lowest stratum a should be about l@ to 1/2 inch mesh, stratum b about 1A; to 41 inch mesh, and stratum c about 11g to 1/8 inch mesh, but such sizes are merely illustrative and not limiting.

Stratum c will comprise the bulli of the contact material and may extend substantially to the overflow for oil and water indicated by the line 0-Il, the remainder of the filling in the upper portion comprising material a.

The oil and water owing upwardly through lthe interstices of the contact material in tower 20 pass therefrom through suitably sized openings provided, which may be of any form adapted not to produce excessive turbulence due to increased velocity therethrough.

As illustrated, one form may include four supports 22 holding up the dome of tower 2c which provide for relatively large openings all shrouded on the inside of the tower by a screen 23 of suitable mesh size adapted to retain all the contact material while permitting the free egress of oil and water to a separating chamber, or launder, 2d encircling the upper portion of tower 26. i

Chamber 2d is of sufllcient size to appreciably diminish the velocity of the oil and water overowing attheline 0-0,so`that practically complete separation of the processed emulsion takes place thus permitting the water to settle below the level G--Q from which it is withdrawn by a pipe 25 while the oil passes off through pipe 26, heat exchanger I 3, pipe 2l, cooler 28 and pipe 2S to storage, or other uses.

A valve 30 serves to drain tower 2li when required and a valve 3| is used to take off any gases from chamber 2t while a required level of separated water, preferably below the level 0 0, can be held in chamber 2t by inspection of gauge 32 so that oil will not be withdrawn through pipe 25.

, Preferably the separated saline water withdrawn through pipe 25, or such part as is required, is passed into an evaporator 33 wherein its salinity is increased to a desired degree and thereafter it is passed through pipe 36 to the inlet side of pump II to be mixed with the incoming oil.

Steam, or other hot fluid medium through pipe 35 may be used to heat the oil in heater I5 and then pas-s through pipe 36 to coil 31 in evaporator 33, or any other suitable heating means can be employed.

From the above description, it may be noted that saline water from evaporator 33 is the medium used to introduce into the stream of oil passing in to the system through pipe l0. An ordinary assumption might be that fresh water would best serve the purpose of removing salt from an oil but on the contrary it is found that by using a .saline water, the concentration of which may be regulated in various ways, desalting and dehydration can be accomplished in a single operation, but in order to accomplish this eiect a thorough mixing of the introduced water with the oil is desirable prior to separation in tower 20.

Accordingly, in operation the oil, whether emulsif'led or not but containing particles of solid salt, is received by pump Il, together with a stream of water of a desired salinity, which mixture, after heating if necessary, is forced into mixer l1 which is of any well known construction adapted to violently agitate the mixture and secure adequate contact of the salt and solution for separation of the salt.

The result of such agitation is to partially or completely emulsify the oil which is then passed into the bottom of tower (which has been initially filled with salt water up to the overow line 0 0) and in passing up through the interstices of the contactmaterial the distortion oi' the emulsied oil globules is such that coalescence of the water therein is effected with the main body of water in tower 20.

While, as to the desalting action alone, it is believed that the yiolent agitation of the oil with the saline solution contributes largely to the desalting action by causing the encased salt particles to be contacted with the solution, yet the action is not completed until contact in tower 20 has been eiected.

'I'his action cannot be fully explained as it is I not fully understood but .the result is as stated;

i. e., the oil is both desalted and dehydrated and it is understood that the desalting action takes place both in the mixer l1 and the tower 20.

It will be understood that the system may be expanded as required to meet varying conditions. For instance, there may be more than one mixer I1 or more than one evaporator 33, or a series of towers like 20 containing a saline solution of such concentration as to provide substantially anhydrous oil.

As illustrative of the process described, .it is possible to reduce theB. S. and water content of an oil from a trace up to two-tenths of one per cent, whereas ordinary crude petroleum is considered to be dehydrated when it contains not in excess of 3% B. S. and W.

The system is highly economical inasmuch as the use of fresh water and fresh salt solution is practically eliminated, inasmuch as a predetermined concentration of brine can be put in a tower and thereafter substantially maintained, as described.

Under conditions that an emulsion of such character is formed and treated in the apparatus of Fig. 1 in which tower sizes, etc., are not favorable to the complete separation of Water, similar instrumentalities may be arranged as shown in Fig. 2'.

In this event, towers A and B are constructed for operation, as previously described.

soli The oil to be treated passes in through pipe 38, pump 39, heater 40, mixer 4I, pipe 42, and distributor into the bottom of a tower A, which is packed with contact material as described, through which the stream of emulsied oil and water passes upwardly to be separated in chamber 44.

If the oil is suflciently dehydrated, it may be passed out of the system through pipe 45, otherwise it will be passed into the bottom of the second tower B, which has initially been filled with a salt solution supplied through pipev 46, and pass thence completely desalted and dehydrated from the system through pipe 41.

With this system, tower A and the admission of oil and saline solution is operated as previously described for tower 20. In some instances. sulicient mixing and emulsifying if al1 the required saline solution is introduced to the oil through pipe 48, or al1 of the saline solution may be introduced through pipe 49 to go directly to the mixer 4|, which may be of the injector type for thorough mixing, or part of the saline solution may be introduced through both pipes 4I and 49.

In order to conserve salt and fresh water or fresh saline solution, it is preferred the separated saline solution from tower A should pass through pipe 50 and a suitable concentrator, or other means to regulate its salinity such as a tower lled with rock salt, and thence into either of pipes 48 or 49, or both.

Any saline solution from tower A, in excess of that required for operating tower A, may either be discharged from the system or passed for use into tower B and the salinity of the water separated in tower B can be maintained or increased by passage through a suitable apparatus 52.

Many variations of flow and treatment of the separated solutions and repeated use are obvious for the purpose and scope of the appended claims, in which I claim:

I claim:

1. A process for desalting oil which comprises: agitating a petroleum oil containing particles of salt with a saline solution to partly dissolve the salt, passing the mixture through a body of contact material to substantially completely dissolve said solid salt in the saline solution, and then immediately separating the solution and oil.

2. A process for desalting oil which comprises: violently agitating a petroleum oil containing particles of solid salt and a saline solution to emulsify at least part of the oil, then completing the dissolution of said solid salt by passing said emulsion through contact material substantially submerged in similar saline solution to force exposure of the salt to said solution through the interstices of the contact material, and then immediately separating the oil and solution.

3. A process for desalting oil which comprises: heating a petroleum oil containing solid salt par- 'cles and a saline solution, agitating the heated oil with the solution to partly emulsify the mixture, passing the mixture as a combined stream through contact material, and thereafter immediately separating the oil and solution.

1. A process for desalting oil which comprises: i

agitating a petroleum oil containing particles of d salt with a saline solution, passing the mixture as a combined stream through a bed of contact material substantially submerged in similar saline solution of predetermined concentration, immediately separating the oil and solution,

and maintaining the concentration of said solution during the continued passage of said comseparating said oil and solution after passage bined stream. through said bed, increasing the salinity of at 5. A continuous cyclic process for desalting oil, least a portion of said separated solution, and which comprises: agitating a petroleum oil concontinuously introducing said solution of intaining solid salt particles with a saline solution, 5 creased salinity to said bed.

passing the mixture as a combined stream 7. Aprocess for desalting oil, which comprises:

through a bed of contact material substantially agitating a petroleum oil containing particles of submerged in similar saline solution,'immediately solid salt with a saline solution to a degree sufseparating said oil and solution after passage flcient to emulsify at least part of the oil. passthrough said bed, increasing the salinity of at l0 ing the mixture upwardly through a bed of conleast a portion of said separated solution, and tact material wherein the salt is completely discontinuously introducing said solution of insolved in the water of said emulsion, separating creased salinity to said agitating step. part of the solution from the oil, then passing the 6. A continuous cyclic process for desalting oil, separated oil through further contact material which comprises: agitating a petroleum oil con- 15 substantially submerged in a saline solution of taining solid salt particles with a. saline solution, greater concentration than said iirst solution to passing the mixture as a combined stream substantially completely separate any of said first through a bed of contact material substantially solution remaining in said oil. submerged in similar saline solution, immediately SUMNER E. CAMPBELL? 

